The present disclosure relates generally to gas turbine engines and, more particularly, to turbine blade sealing structures. Specifically, the disclosure concerns probes within turbine blade sealing structures.
A gas turbine engine typically includes a high-pressure spool, a combustion system, and a low-pressure spool disposed within an engine case to form a generally axial, serial flow path about the engine centerline. The high-pressure spool includes a high-pressure turbine, a high-pressure shaft extending axially forward from the high-pressure turbine, and a high-pressure compressor connected to a forward end of the high-pressure shaft. The low-pressure spool includes a low-pressure turbine, which is disposed downstream of the high-pressure turbine, a low-pressure shaft, which typically extends coaxially through the high-pressure shaft, and a low-pressure compressor connected to a forward end of the low-pressure shaft, forward of the high-pressure compressor. The combustion system is disposed between the high-pressure compressor and the high-pressure turbine and receives compressed air from the compressors and fuel provided by a fuel injection system. A combustion process is carried out within the combustion system to produce high-energy gases to produce thrust and turn the high- and low-pressure turbines, which drive the compressors to sustain the combustion process.
Turbine blade outer air seals (BOAS) seal turbine gas path air between the rotating blades of the turbine and the gas path surface of a casing. The distance between the tip of the blades and the surface of the BOAS greatly impacts turbine efficiency. Reducing that distance as much as possible improves engine efficiency. Accordingly, efforts have been made to monitor blade tip clearance during engine operation. However, extremely high temperatures in the gas path often make such monitoring difficult.
The operating temperature of a typical probe is lower than that of the gas path of a turbine engine. Current methods of cooling probe tips exposed to the gas path include supplying cooling air from an external cooling source. Cooling a probe tip in this manner necessitates a coolant, such as liquid nitrogen, and plumbing to deliver the coolant to the probe tip.